numam-spdk/lib/vhost/vhost_scsi.c

/*-
 *   BSD LICENSE
 *
 *   Copyright(c) Intel Corporation. All rights reserved.
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "spdk/stdinc.h"

#include <linux/virtio_scsi.h>

#include "spdk/env.h"
#include "spdk/scsi.h"
#include "spdk/scsi_spec.h"
#include "spdk/conf.h"
#include "spdk/event.h"
#include "spdk/util.h"
#include "spdk/likely.h"

#include "spdk/vhost.h"
#include "vhost_internal.h"

/* Features supported by SPDK VHOST lib. */
#define SPDK_VHOST_SCSI_FEATURES	(SPDK_VHOST_FEATURES | \
					(1ULL << VIRTIO_SCSI_F_INOUT) | \
					(1ULL << VIRTIO_SCSI_F_HOTPLUG) | \
					(1ULL << VIRTIO_SCSI_F_CHANGE ) | \
					(1ULL << VIRTIO_SCSI_F_T10_PI ))

/* Features that are specified in VIRTIO SCSI but currently not supported:
 * - Live migration not supported yet
 * - T10 PI
 */
#define SPDK_VHOST_SCSI_DISABLED_FEATURES	(SPDK_VHOST_DISABLED_FEATURES | \
						(1ULL << VIRTIO_SCSI_F_T10_PI ))

#define MGMT_POLL_PERIOD_US (1000 * 5)

#define VIRTIO_SCSI_CONTROLQ   0
#define VIRTIO_SCSI_EVENTQ   1
#define VIRTIO_SCSI_REQUESTQ   2

struct spdk_scsi_dev_vhost_state {
	bool removed;
	spdk_vhost_event_fn remove_cb;
	void *remove_ctx;
};

struct spdk_vhost_scsi_dev {
	struct spdk_vhost_dev vdev;
	struct spdk_scsi_dev *scsi_dev[SPDK_VHOST_SCSI_CTRLR_MAX_DEVS];
	struct spdk_scsi_dev_vhost_state scsi_dev_state[SPDK_VHOST_SCSI_CTRLR_MAX_DEVS];

	struct spdk_poller *requestq_poller;
	struct spdk_poller *mgmt_poller;
} __rte_cache_aligned;

struct spdk_vhost_scsi_task {
	struct spdk_scsi_task	scsi;
	struct iovec iovs[SPDK_VHOST_IOVS_MAX];

	union {
		struct virtio_scsi_cmd_resp *resp;
		struct virtio_scsi_ctrl_tmf_resp *tmf_resp;
	};

	struct spdk_vhost_scsi_dev *svdev;
	struct spdk_scsi_dev *scsi_dev;

	int req_idx;

	/* If set, the task is currently used for I/O processing. */
	bool used;

	struct spdk_vhost_virtqueue *vq;
};

static int spdk_vhost_scsi_start(struct spdk_vhost_dev *, void *);
static int spdk_vhost_scsi_stop(struct spdk_vhost_dev *, void *);
static void spdk_vhost_scsi_config_json(struct spdk_vhost_dev *vdev, struct spdk_json_write_ctx *w);

const struct spdk_vhost_dev_backend spdk_vhost_scsi_device_backend = {
	.virtio_features = SPDK_VHOST_SCSI_FEATURES,
	.disabled_features = SPDK_VHOST_SCSI_DISABLED_FEATURES,
	.start_device =  spdk_vhost_scsi_start,
	.stop_device = spdk_vhost_scsi_stop,
	.dump_config_json = spdk_vhost_scsi_config_json,
	.vhost_remove_controller = spdk_vhost_scsi_dev_remove,
};

static void
spdk_vhost_scsi_task_put(struct spdk_vhost_scsi_task *task)
{
	spdk_scsi_task_put(&task->scsi);
}

static void
spdk_vhost_scsi_task_free_cb(struct spdk_scsi_task *scsi_task)
{
	struct spdk_vhost_scsi_task *task = SPDK_CONTAINEROF(scsi_task, struct spdk_vhost_scsi_task, scsi);

	assert(task->svdev->vdev.task_cnt > 0);
	task->svdev->vdev.task_cnt--;
	task->used = false;
}

static void
process_removed_devs(struct spdk_vhost_scsi_dev *svdev)
{
	struct spdk_scsi_dev *dev;
	struct spdk_scsi_dev_vhost_state *state;
	int i;

	for (i = 0; i < SPDK_VHOST_SCSI_CTRLR_MAX_DEVS; ++i) {
		dev = svdev->scsi_dev[i];
		state = &svdev->scsi_dev_state[i];

		if (dev && state->removed && !spdk_scsi_dev_has_pending_tasks(dev)) {
			spdk_scsi_dev_free_io_channels(dev);
			spdk_scsi_dev_destruct(dev);
			svdev->scsi_dev[i] = NULL;
			if (state->remove_cb) {
				state->remove_cb(&svdev->vdev, state->remove_ctx);
				state->remove_cb = NULL;
			}
			SPDK_NOTICELOG("%s: hot-detached device 'Dev %u'.\n", svdev->vdev.name, i);
		}
	}
}

static void
eventq_enqueue(struct spdk_vhost_scsi_dev *svdev, unsigned scsi_dev_num, uint32_t event,
	       uint32_t reason)
{
	struct spdk_vhost_virtqueue *vq;
	struct vring_desc *desc, *desc_table;
	struct virtio_scsi_event *desc_ev;
	uint32_t desc_table_size, req_size = 0;
	uint16_t req;
	int rc;

	assert(scsi_dev_num < SPDK_VHOST_SCSI_CTRLR_MAX_DEVS);
	vq = &svdev->vdev.virtqueue[VIRTIO_SCSI_EVENTQ];

	if (spdk_vhost_vq_avail_ring_get(vq, &req, 1) != 1) {
		SPDK_ERRLOG("Controller %s: Failed to send virtio event (no avail ring entries?).\n",
			    svdev->vdev.name);
		return;
	}

	rc = spdk_vhost_vq_get_desc(&svdev->vdev, vq, req, &desc, &desc_table, &desc_table_size);
	if (rc != 0 || desc->len < sizeof(*desc_ev)) {
		SPDK_ERRLOG("Controller %s: Invalid eventq descriptor at index %"PRIu16".\n",
			    svdev->vdev.name, req);
		goto out;
	}

	desc_ev = spdk_vhost_gpa_to_vva(&svdev->vdev, desc->addr);
	if (desc_ev == NULL) {
		SPDK_ERRLOG("Controller %s: Eventq descriptor at index %"PRIu16" points to unmapped guest memory address %p.\n",
			    svdev->vdev.name, req, (void *)(uintptr_t)desc->addr);
		goto out;
	}

	desc_ev->event = event;
	desc_ev->lun[0] = 1;
	desc_ev->lun[1] = scsi_dev_num;
	/* virtio LUN id 0 can refer either to the entire device
	 * or actual LUN 0 (the only supported by vhost for now)
	 */
	desc_ev->lun[2] = 0 >> 8;
	desc_ev->lun[3] = 0 & 0xFF;
	/* virtio doesn't specify any strict format for LUN id (bytes 2 and 3)
	 * current implementation relies on linux kernel sources
	 */
	memset(&desc_ev->lun[4], 0, 4);
	desc_ev->reason = reason;
	req_size = sizeof(*desc_ev);

out:
	spdk_vhost_vq_used_ring_enqueue(&svdev->vdev, vq, req, req_size);
}

static void
submit_completion(struct spdk_vhost_scsi_task *task)
{
	spdk_vhost_vq_used_ring_enqueue(&task->svdev->vdev, task->vq, task->req_idx,
					task->scsi.data_transferred);
	SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI, "Finished task (%p) req_idx=%d\n", task, task->req_idx);

	spdk_vhost_scsi_task_put(task);
}

static void
spdk_vhost_scsi_task_mgmt_cpl(struct spdk_scsi_task *scsi_task)
{
	struct spdk_vhost_scsi_task *task = SPDK_CONTAINEROF(scsi_task, struct spdk_vhost_scsi_task, scsi);

	submit_completion(task);
}

static void
spdk_vhost_scsi_task_cpl(struct spdk_scsi_task *scsi_task)
{
	struct spdk_vhost_scsi_task *task = SPDK_CONTAINEROF(scsi_task, struct spdk_vhost_scsi_task, scsi);

	/* The SCSI task has completed.  Do final processing and then post
	   notification to the virtqueue's "used" ring.
	 */
	task->resp->status = task->scsi.status;

	if (task->scsi.status != SPDK_SCSI_STATUS_GOOD) {
		memcpy(task->resp->sense, task->scsi.sense_data, task->scsi.sense_data_len);
		task->resp->sense_len = task->scsi.sense_data_len;
	}
	task->resp->resid = task->scsi.transfer_len - task->scsi.data_transferred;

	submit_completion(task);
}

static void
task_submit(struct spdk_vhost_scsi_task *task)
{
	task->resp->response = VIRTIO_SCSI_S_OK;
	spdk_scsi_dev_queue_task(task->scsi_dev, &task->scsi);
}

static void
mgmt_task_submit(struct spdk_vhost_scsi_task *task, enum spdk_scsi_task_func func)
{
	task->tmf_resp->response = VIRTIO_SCSI_S_OK;
	spdk_scsi_dev_queue_mgmt_task(task->scsi_dev, &task->scsi, func);
}

static void
invalid_request(struct spdk_vhost_scsi_task *task)
{
	spdk_vhost_vq_used_ring_enqueue(&task->svdev->vdev, task->vq, task->req_idx, 0);
	spdk_vhost_scsi_task_put(task);

	SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI, "Invalid request (status=%" PRIu8")\n",
		      task->resp ? task->resp->response : -1);
}

static int
spdk_vhost_scsi_task_init_target(struct spdk_vhost_scsi_task *task, const __u8 *lun)
{
	struct spdk_scsi_dev *dev;
	uint16_t lun_id = (((uint16_t)lun[2] << 8) | lun[3]) & 0x3FFF;

	SPDK_TRACEDUMP(SPDK_TRACE_VHOST_SCSI_QUEUE, "LUN", lun, 8);

	/* First byte must be 1 and second is target */
	if (lun[0] != 1 || lun[1] >= SPDK_VHOST_SCSI_CTRLR_MAX_DEVS)
		return -1;

	dev = task->svdev->scsi_dev[lun[1]];
	task->scsi_dev = dev;
	if (dev == NULL || task->svdev->scsi_dev_state[lun[1]].removed) {
		/* If dev has been hotdetached, return 0 to allow sending
		 * additional hotremove event via sense codes.
		 */
		return task->svdev->scsi_dev_state[lun[1]].removed ? 0 : -1;
	}

	task->scsi.target_port = spdk_scsi_dev_find_port_by_id(task->scsi_dev, 0);
	task->scsi.lun = spdk_scsi_dev_get_lun(dev, lun_id);
	return 0;
}

static void
process_ctrl_request(struct spdk_vhost_scsi_task *task)
{
	struct spdk_vhost_dev *vdev = &task->svdev->vdev;
	struct vring_desc *desc, *desc_table;
	struct virtio_scsi_ctrl_tmf_req *ctrl_req;
	struct virtio_scsi_ctrl_an_resp *an_resp;
	uint32_t desc_table_size;
	int rc;

	spdk_scsi_task_construct(&task->scsi, spdk_vhost_scsi_task_mgmt_cpl, spdk_vhost_scsi_task_free_cb,
				 NULL);
	rc = spdk_vhost_vq_get_desc(vdev, task->vq, task->req_idx, &desc, &desc_table, &desc_table_size);
	if (spdk_unlikely(rc != 0)) {
		SPDK_ERRLOG("%s: Invalid controlq descriptor at index %d.\n",
			    vdev->name, task->req_idx);
		goto out;
	}

	ctrl_req = spdk_vhost_gpa_to_vva(vdev, desc->addr);

	SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI_QUEUE,
		      "Processing controlq descriptor: desc %d/%p, desc_addr %p, len %d, flags %d, last_used_idx %d; kickfd %d; size %d\n",
		      task->req_idx, desc, (void *)desc->addr, desc->len, desc->flags, task->vq->vring.last_used_idx,
		      task->vq->vring.kickfd, task->vq->vring.size);
	SPDK_TRACEDUMP(SPDK_TRACE_VHOST_SCSI_QUEUE, "Request descriptor", (uint8_t *)ctrl_req,
		       desc->len);

	spdk_vhost_scsi_task_init_target(task, ctrl_req->lun);

	spdk_vhost_vring_desc_get_next(&desc, desc_table, desc_table_size);
	if (spdk_unlikely(desc == NULL)) {
		SPDK_ERRLOG("%s: No response descriptor for controlq request %d.\n",
			    vdev->name, task->req_idx);
		goto out;
	}

	/* Process the TMF request */
	switch (ctrl_req->type) {
	case VIRTIO_SCSI_T_TMF:
		task->tmf_resp = spdk_vhost_gpa_to_vva(vdev, desc->addr);
		if (spdk_unlikely(desc->len < sizeof(struct virtio_scsi_ctrl_tmf_resp) || task->tmf_resp == NULL)) {
			SPDK_ERRLOG("%s: TMF response descriptor at index %d points to invalid guest memory region\n",
				    vdev->name, task->req_idx);
			goto out;
		}

		/* Check if we are processing a valid request */
		if (task->scsi_dev == NULL) {
			task->tmf_resp->response = VIRTIO_SCSI_S_BAD_TARGET;
			break;
		}

		switch (ctrl_req->subtype) {
		case VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET:
			/* Handle LUN reset */
			SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI_QUEUE, "LUN reset\n");

			mgmt_task_submit(task, SPDK_SCSI_TASK_FUNC_LUN_RESET);
			return;
		default:
			task->tmf_resp->response = VIRTIO_SCSI_S_ABORTED;
			/* Unsupported command */
			SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI_QUEUE, "Unsupported TMF command %x\n", ctrl_req->subtype);
			break;
		}
		break;
	case VIRTIO_SCSI_T_AN_QUERY:
	case VIRTIO_SCSI_T_AN_SUBSCRIBE: {
		an_resp = spdk_vhost_gpa_to_vva(vdev, desc->addr);
		if (spdk_unlikely(desc->len < sizeof(struct virtio_scsi_ctrl_an_resp) || an_resp == NULL)) {
			SPDK_WARNLOG("%s: Asynchronous response descriptor points to invalid guest memory region\n",
				     vdev->name);
			goto out;
		}

		an_resp->response = VIRTIO_SCSI_S_ABORTED;
		break;
	}
	default:
		SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI_QUEUE, "Unsupported control command %x\n", ctrl_req->type);
		break;
	}

out:
	spdk_vhost_vq_used_ring_enqueue(vdev, task->vq, task->req_idx, 0);
	spdk_vhost_scsi_task_put(task);
}

/*
 * Process task's descriptor chain and setup data related fields.
 * Return
 *   -1 if request is invalid and must be aborted,
 *    0 if all data are set.
 */
static int
task_data_setup(struct spdk_vhost_scsi_task *task,
		struct virtio_scsi_cmd_req **req)
{
	struct spdk_vhost_dev *vdev = &task->svdev->vdev;
	struct vring_desc *desc, *desc_table;
	struct iovec *iovs = task->iovs;
	uint16_t iovcnt = 0, iovcnt_max = SPDK_VHOST_IOVS_MAX;
	uint32_t desc_table_len, len = 0;
	int rc;

	spdk_scsi_task_construct(&task->scsi, spdk_vhost_scsi_task_cpl, spdk_vhost_scsi_task_free_cb, NULL);

	rc = spdk_vhost_vq_get_desc(vdev, task->vq, task->req_idx, &desc, &desc_table, &desc_table_len);
	/* First descriptor must be readable */
	if (spdk_unlikely(rc != 0  || spdk_vhost_vring_desc_is_wr(desc) ||
			  desc->len < sizeof(struct virtio_scsi_cmd_req))) {
		SPDK_WARNLOG("%s: invalid first (request) descriptor at index %"PRIu16".\n",
			     vdev->name, task->req_idx);
		goto invalid_task;
	}

	*req = spdk_vhost_gpa_to_vva(vdev, desc->addr);
	if (spdk_unlikely(*req == NULL)) {
		SPDK_WARNLOG("%s: Request descriptor at index %d points to invalid guest memory region\n",
			     vdev->name, task->req_idx);
		goto invalid_task;
	}

	/* Each request must have at least 2 descriptors (e.g. request and response) */
	spdk_vhost_vring_desc_get_next(&desc, desc_table, desc_table_len);
	if (desc == NULL) {
		SPDK_WARNLOG("%s: Descriptor chain at index %d contains neither payload nor response buffer.\n",
			     vdev->name, task->req_idx);
		goto invalid_task;
	}
	task->scsi.dxfer_dir = spdk_vhost_vring_desc_is_wr(desc) ? SPDK_SCSI_DIR_FROM_DEV :
			       SPDK_SCSI_DIR_TO_DEV;
	task->scsi.iovs = iovs;

	if (task->scsi.dxfer_dir == SPDK_SCSI_DIR_FROM_DEV) {
		/*
		 * FROM_DEV (READ): [RD_req][WR_resp][WR_buf0]...[WR_bufN]
		 */
		task->resp = spdk_vhost_gpa_to_vva(vdev, desc->addr);
		if (spdk_unlikely(desc->len < sizeof(struct virtio_scsi_cmd_resp) || task->resp == NULL)) {
			SPDK_WARNLOG("%s: Response descriptor at index %d points to invalid guest memory region\n",
				     vdev->name, task->req_idx);
			goto invalid_task;
		}
		rc = spdk_vhost_vring_desc_get_next(&desc, desc_table, desc_table_len);
		if (spdk_unlikely(rc != 0)) {
			SPDK_WARNLOG("%s: invalid descriptor chain at request index %d (descriptor id overflow?).\n",
				     vdev->name, task->req_idx);
			goto invalid_task;
		}

		if (desc == NULL) {
			/*
			 * TEST UNIT READY command and some others might not contain any payload and this is not an error.
			 */
			SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI_DATA,
				      "No payload descriptors for FROM DEV command req_idx=%"PRIu16".\n", task->req_idx);
			SPDK_TRACEDUMP(SPDK_TRACE_VHOST_SCSI_DATA, "CDB=", (*req)->cdb, VIRTIO_SCSI_CDB_SIZE);
			task->scsi.iovcnt = 1;
			task->scsi.iovs[0].iov_len = 0;
			task->scsi.length = 0;
			task->scsi.transfer_len = 0;
			return 0;
		}

		/* All remaining descriptors are data. */
		while (desc && iovcnt < iovcnt_max) {
			if (spdk_unlikely(!spdk_vhost_vring_desc_is_wr(desc))) {
				SPDK_WARNLOG("FROM DEV cmd: descriptor nr %" PRIu16" in payload chain is read only.\n", iovcnt);
				goto invalid_task;
			}

			if (spdk_unlikely(spdk_vhost_vring_desc_to_iov(vdev, iovs, &iovcnt, desc))) {
				goto invalid_task;
			}
			len += desc->len;

			rc = spdk_vhost_vring_desc_get_next(&desc, desc_table, desc_table_len);
			if (spdk_unlikely(rc != 0)) {
				SPDK_WARNLOG("%s: invalid payload in descriptor chain starting at index %d.\n",
					     vdev->name, task->req_idx);
				goto invalid_task;
			}
		}
	} else {
		SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI_DATA, "TO DEV");
		/*
		 * TO_DEV (WRITE):[RD_req][RD_buf0]...[RD_bufN][WR_resp]
		 * No need to check descriptor WR flag as this is done while setting scsi.dxfer_dir.
		 */

		/* Process descriptors up to response. */
		while (!spdk_vhost_vring_desc_is_wr(desc) && iovcnt < iovcnt_max) {
			if (spdk_unlikely(spdk_vhost_vring_desc_to_iov(vdev, iovs, &iovcnt, desc))) {
				goto invalid_task;
			}
			len += desc->len;

			spdk_vhost_vring_desc_get_next(&desc, desc_table, desc_table_len);
			if (spdk_unlikely(desc == NULL)) {
				SPDK_WARNLOG("TO_DEV cmd: no response descriptor.\n");
				goto invalid_task;
			}
		}

		task->resp = spdk_vhost_gpa_to_vva(vdev, desc->addr);
		if (spdk_unlikely(desc->len < sizeof(struct virtio_scsi_cmd_resp) || task->resp == NULL)) {
			SPDK_WARNLOG("%s: Response descriptor at index %d points to invalid guest memory region\n",
				     vdev->name, task->req_idx);
			goto invalid_task;
		}
	}

	if (iovcnt == iovcnt_max) {
		SPDK_WARNLOG("Too many IO vectors in chain!\n");
		task->resp->response = VIRTIO_SCSI_S_ABORTED;
		goto invalid_task;
	}

	task->scsi.iovcnt = iovcnt;
	task->scsi.length = len;
	task->scsi.transfer_len = len;
	return 0;

invalid_task:
	SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI_DATA, "%s: Invalid task at index %"PRIu16".\n",
		      vdev->name, task->req_idx);
	return -1;
}

static int
process_request(struct spdk_vhost_scsi_task *task)
{
	struct virtio_scsi_cmd_req *req;
	int result;

	result = task_data_setup(task, &req);
	if (result) {
		return result;
	}

	result = spdk_vhost_scsi_task_init_target(task, req->lun);
	if (spdk_unlikely(result != 0)) {
		task->resp->response = VIRTIO_SCSI_S_BAD_TARGET;
		return -1;
	}

	task->scsi.cdb = req->cdb;
	SPDK_TRACEDUMP(SPDK_TRACE_VHOST_SCSI_DATA, "request CDB", req->cdb, VIRTIO_SCSI_CDB_SIZE);

	if (spdk_unlikely(task->scsi.lun == NULL)) {
		spdk_scsi_task_process_null_lun(&task->scsi);
		task->resp->response = VIRTIO_SCSI_S_OK;
		return 1;
	}

	return 0;
}

static void
process_controlq(struct spdk_vhost_scsi_dev *svdev, struct spdk_vhost_virtqueue *vq)
{
	struct spdk_vhost_scsi_task *task;
	uint16_t reqs[32];
	uint16_t reqs_cnt, i;

	reqs_cnt = spdk_vhost_vq_avail_ring_get(vq, reqs, SPDK_COUNTOF(reqs));
	for (i = 0; i < reqs_cnt; i++) {
		if (spdk_unlikely(reqs[i] >= vq->vring.size)) {
			SPDK_ERRLOG("%s: invalid entry in avail ring. Buffer '%"PRIu16"' exceeds virtqueue size (%"PRIu16")\n",
				    svdev->vdev.name, reqs[i], vq->vring.size);
			spdk_vhost_vq_used_ring_enqueue(&svdev->vdev, vq, reqs[i], 0);
			continue;
		}

		task = &((struct spdk_vhost_scsi_task *)vq->tasks)[reqs[i]];
		if (spdk_unlikely(task->used)) {
			SPDK_ERRLOG("%s: invalid entry in avail ring. Buffer '%"PRIu16"' is still in use!\n",
				    svdev->vdev.name, reqs[i]);
			spdk_vhost_vq_used_ring_enqueue(&svdev->vdev, vq, reqs[i], 0);
			continue;
		}

		svdev->vdev.task_cnt++;
		memset(&task->scsi, 0, sizeof(task->scsi));
		task->tmf_resp = NULL;
		task->used = true;
		process_ctrl_request(task);
	}
}

static void
process_requestq(struct spdk_vhost_scsi_dev *svdev, struct spdk_vhost_virtqueue *vq)
{
	struct spdk_vhost_scsi_task *task;
	uint16_t reqs[32];
	uint16_t reqs_cnt, i;
	int result;

	reqs_cnt = spdk_vhost_vq_avail_ring_get(vq, reqs, SPDK_COUNTOF(reqs));
	assert(reqs_cnt <= 32);

	for (i = 0; i < reqs_cnt; i++) {
		SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI, "====== Starting processing request idx %"PRIu16"======\n",
			      reqs[i]);

		if (spdk_unlikely(reqs[i] >= vq->vring.size)) {
			SPDK_ERRLOG("%s: request idx '%"PRIu16"' exceeds virtqueue size (%"PRIu16").\n",
				    svdev->vdev.name, reqs[i], vq->vring.size);
			spdk_vhost_vq_used_ring_enqueue(&svdev->vdev, vq, reqs[i], 0);
			continue;
		}

		task = &((struct spdk_vhost_scsi_task *)vq->tasks)[reqs[i]];
		if (spdk_unlikely(task->used)) {
			SPDK_ERRLOG("%s: request with idx '%"PRIu16"' is already pending.\n",
				    svdev->vdev.name, reqs[i]);
			spdk_vhost_vq_used_ring_enqueue(&svdev->vdev, vq, reqs[i], 0);
			continue;
		}

		svdev->vdev.task_cnt++;
		memset(&task->scsi, 0, sizeof(task->scsi));
		task->resp = NULL;
		task->used = true;
		result = process_request(task);
		if (likely(result == 0)) {
			task_submit(task);
			SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI, "====== Task %p req_idx %d submitted ======\n", task,
				      task->req_idx);
		} else if (result > 0) {
			spdk_vhost_scsi_task_cpl(&task->scsi);
			SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI, "====== Task %p req_idx %d finished early ======\n", task,
				      task->req_idx);
		} else {
			invalid_request(task);
			SPDK_DEBUGLOG(SPDK_TRACE_VHOST_SCSI, "====== Task %p req_idx %d failed ======\n", task,
				      task->req_idx);
		}
	}
}

static void
vdev_mgmt_worker(void *arg)
{
	struct spdk_vhost_scsi_dev *svdev = arg;

	process_removed_devs(svdev);
	spdk_vhost_vq_used_signal(&svdev->vdev, &svdev->vdev.virtqueue[VIRTIO_SCSI_EVENTQ]);

	process_controlq(svdev, &svdev->vdev.virtqueue[VIRTIO_SCSI_CONTROLQ]);
	spdk_vhost_vq_used_signal(&svdev->vdev, &svdev->vdev.virtqueue[VIRTIO_SCSI_CONTROLQ]);
}

static void
vdev_worker(void *arg)
{
	struct spdk_vhost_scsi_dev *svdev = arg;
	uint32_t q_idx;

	for (q_idx = VIRTIO_SCSI_REQUESTQ; q_idx < svdev->vdev.num_queues; q_idx++) {
		process_requestq(svdev, &svdev->vdev.virtqueue[q_idx]);
	}

	spdk_vhost_dev_used_signal(&svdev->vdev);
}

static struct spdk_vhost_scsi_dev *
to_scsi_dev(struct spdk_vhost_dev *ctrlr)
{
	if (ctrlr == NULL) {
		return NULL;
	}

	if (ctrlr->type != SPDK_VHOST_DEV_T_SCSI) {
		SPDK_ERRLOG("Controller %s: expected SCSI controller (%d) but got %d\n",
			    ctrlr->name, SPDK_VHOST_DEV_T_SCSI, ctrlr->type);
		return NULL;
	}

	return (struct spdk_vhost_scsi_dev *)ctrlr;
}

int
spdk_vhost_scsi_dev_construct(const char *name, const char *cpumask)
{
	struct spdk_vhost_scsi_dev *svdev = spdk_dma_zmalloc(sizeof(struct spdk_vhost_scsi_dev),
					    SPDK_CACHE_LINE_SIZE, NULL);
	int rc;

	if (svdev == NULL) {
		return -ENOMEM;
	}

	spdk_vhost_lock();
	rc = spdk_vhost_dev_construct(&svdev->vdev, name, cpumask, SPDK_VHOST_DEV_T_SCSI,
				      &spdk_vhost_scsi_device_backend);

	if (rc) {
		spdk_dma_free(svdev);
	}

	spdk_vhost_unlock();
	return rc;
}

int
spdk_vhost_scsi_dev_remove(struct spdk_vhost_dev *vdev)
{
	struct spdk_vhost_scsi_dev *svdev = to_scsi_dev(vdev);
	int rc, i;

	if (svdev == NULL) {
		return -EINVAL;
	}

	for (i = 0; i < SPDK_VHOST_SCSI_CTRLR_MAX_DEVS; ++i) {
		if (svdev->scsi_dev[i]) {
			SPDK_ERRLOG("Trying to remove non-empty controller: %s.\n", vdev->name);
			return -EBUSY;
		}
	}

	rc = spdk_vhost_dev_remove(vdev);
	if (rc != 0) {
		return rc;
	}

	spdk_dma_free(svdev);
	return 0;
}

struct spdk_scsi_dev *
spdk_vhost_scsi_dev_get_dev(struct spdk_vhost_dev *vdev, uint8_t num)
{
	struct spdk_vhost_scsi_dev *svdev;

	assert(num < SPDK_VHOST_SCSI_CTRLR_MAX_DEVS);
	svdev = to_scsi_dev(vdev);

	return svdev ? svdev->scsi_dev[num] : NULL;
}

static void
spdk_vhost_scsi_lun_hotremove(const struct spdk_scsi_lun *lun, void *arg)
{
	struct spdk_vhost_scsi_dev *svdev = arg;
	const struct spdk_scsi_dev *scsi_dev;
	unsigned scsi_dev_num;

	assert(lun != NULL);
	assert(svdev != NULL);
	if (!spdk_vhost_dev_has_feature(&svdev->vdev, VIRTIO_SCSI_F_HOTPLUG)) {
		SPDK_WARNLOG("%s: hotremove is not enabled for this controller.\n", svdev->vdev.name);
		return;
	}

	scsi_dev = spdk_scsi_lun_get_dev(lun);
	for (scsi_dev_num = 0; scsi_dev_num < SPDK_VHOST_SCSI_CTRLR_MAX_DEVS; scsi_dev_num++) {
		if (svdev->scsi_dev[scsi_dev_num] == scsi_dev) {
			break;
		}
	}

	if (scsi_dev_num == SPDK_VHOST_SCSI_CTRLR_MAX_DEVS) {
		SPDK_ERRLOG("Dev %s is not a part of vhost scsi controller '%s'.\n",
			    spdk_scsi_dev_get_name(scsi_dev),
			    svdev->vdev.name);
		return;
	}

	/* remove entire device */
	spdk_vhost_scsi_dev_remove_dev(&svdev->vdev, scsi_dev_num, NULL, NULL);
}

int
spdk_vhost_scsi_dev_add_dev(struct spdk_vhost_dev *vdev, unsigned scsi_dev_num,
			    const char *lun_name)
{
	struct spdk_vhost_scsi_dev *svdev;
	char dev_name[SPDK_SCSI_DEV_MAX_NAME];
	int lun_id_list[1];
	char *lun_names_list[1];

	svdev = to_scsi_dev(vdev);
	if (svdev == NULL) {
		return -EINVAL;
	}

	if (scsi_dev_num >= SPDK_VHOST_SCSI_CTRLR_MAX_DEVS) {
		SPDK_ERRLOG("Controller %d device number too big (max %d)\n", scsi_dev_num,
			    SPDK_VHOST_SCSI_CTRLR_MAX_DEVS);
		return -EINVAL;
	}

	if (lun_name == NULL) {
		SPDK_ERRLOG("No lun name specified \n");
		return -EINVAL;
	} else if (strlen(lun_name) >= SPDK_SCSI_DEV_MAX_NAME) {
		SPDK_ERRLOG("LUN name '%s' too long (max %d).\n", lun_name, SPDK_SCSI_DEV_MAX_NAME - 1);
		return -1;
	}

	svdev = to_scsi_dev(vdev);
	if (svdev == NULL) {
		return -EINVAL;
	}

	if (vdev->lcore != -1 && !spdk_vhost_dev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
		SPDK_ERRLOG("Controller %s is in use and hotplug is not supported\n", vdev->name);
		return -ENOTSUP;
	}

	if (svdev->scsi_dev[scsi_dev_num] != NULL) {
		SPDK_ERRLOG("Controller %s dev %u already occupied\n", vdev->name, scsi_dev_num);
		return -EEXIST;
	}

	/*
	 * At this stage only one LUN per device
	 */
	snprintf(dev_name, sizeof(dev_name), "Dev %u", scsi_dev_num);
	lun_id_list[0] = 0;
	lun_names_list[0] = (char *)lun_name;

	svdev->scsi_dev_state[scsi_dev_num].removed = false;
	svdev->scsi_dev[scsi_dev_num] = spdk_scsi_dev_construct(dev_name, lun_names_list, lun_id_list, 1,
					SPDK_SPC_PROTOCOL_IDENTIFIER_SAS, spdk_vhost_scsi_lun_hotremove, svdev);

	if (svdev->scsi_dev[scsi_dev_num] == NULL) {
		SPDK_ERRLOG("Couldn't create spdk SCSI device '%s' using lun device '%s' in controller: %s\n",
			    dev_name, lun_name, vdev->name);
		return -EINVAL;
	}
	spdk_scsi_dev_add_port(svdev->scsi_dev[scsi_dev_num], 0, "vhost");

	if (vdev->lcore != -1) {
		spdk_scsi_dev_allocate_io_channels(svdev->scsi_dev[scsi_dev_num]);
		eventq_enqueue(svdev, scsi_dev_num, VIRTIO_SCSI_T_TRANSPORT_RESET, VIRTIO_SCSI_EVT_RESET_RESCAN);
	}

	SPDK_NOTICELOG("Controller %s: defined device '%s' using lun '%s'\n",
		       vdev->name, dev_name, lun_name);
	return 0;
}

int
spdk_vhost_scsi_dev_remove_dev(struct spdk_vhost_dev *vdev, unsigned scsi_dev_num,
			       spdk_vhost_event_fn cb_fn, void *cb_arg)
{
	struct spdk_vhost_scsi_dev *svdev;
	struct spdk_scsi_dev *scsi_dev;
	struct spdk_scsi_dev_vhost_state *scsi_dev_state;
	int rc = 0;

	if (scsi_dev_num >= SPDK_VHOST_SCSI_CTRLR_MAX_DEVS) {
		SPDK_ERRLOG("%s: invalid device number %d\n", vdev->name, scsi_dev_num);
		return -EINVAL;
	}

	svdev = to_scsi_dev(vdev);
	if (svdev == NULL) {
		return -ENODEV;
	}

	scsi_dev = svdev->scsi_dev[scsi_dev_num];
	if (scsi_dev == NULL) {
		SPDK_ERRLOG("Controller %s dev %u is not occupied\n", vdev->name, scsi_dev_num);
		return -ENODEV;
	}

	if (svdev->vdev.lcore == -1) {
		/* controller is not in use, remove dev and exit */
		spdk_scsi_dev_destruct(scsi_dev);
		svdev->scsi_dev[scsi_dev_num] = NULL;
		if (cb_fn) {
			rc = cb_fn(vdev, cb_arg);
		}
		SPDK_NOTICELOG("%s: removed device 'Dev %u'\n", vdev->name, scsi_dev_num);
		return rc;
	}

	if (!spdk_vhost_dev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
		SPDK_WARNLOG("%s: 'Dev %u' is in use and hot-detach is not enabled for this controller.\n",
			     svdev->vdev.name, scsi_dev_num);
		return -ENOTSUP;
	}

	scsi_dev_state = &svdev->scsi_dev_state[scsi_dev_num];
	if (scsi_dev_state->removed) {
		SPDK_WARNLOG("%s: 'Dev %u' has been already marked to hotremove.\n", svdev->vdev.name,
			     scsi_dev_num);
		return -EBUSY;
	}

	scsi_dev_state->remove_cb = cb_fn;
	scsi_dev_state->remove_ctx = cb_arg;
	scsi_dev_state->removed = true;
	eventq_enqueue(svdev, scsi_dev_num, VIRTIO_SCSI_T_TRANSPORT_RESET, VIRTIO_SCSI_EVT_RESET_REMOVED);

	SPDK_NOTICELOG("%s: queued 'Dev %u' for hot-detach.\n", vdev->name, scsi_dev_num);
	return 0;
}

int
spdk_vhost_scsi_controller_construct(void)
{
	struct spdk_conf_section *sp = spdk_conf_first_section(NULL);
	struct spdk_vhost_dev *vdev;
	int i, dev_num;
	unsigned ctrlr_num = 0;
	char *lun_name, *dev_num_str;
	char *cpumask;
	char *name;

	while (sp != NULL) {
		if (!spdk_conf_section_match_prefix(sp, "VhostScsi")) {
			sp = spdk_conf_next_section(sp);
			continue;
		}

		if (sscanf(spdk_conf_section_get_name(sp), "VhostScsi%u", &ctrlr_num) != 1) {
			SPDK_ERRLOG("Section '%s' has non-numeric suffix.\n",
				    spdk_conf_section_get_name(sp));
			return -1;
		}

		name =  spdk_conf_section_get_val(sp, "Name");
		cpumask = spdk_conf_section_get_val(sp, "Cpumask");

		if (spdk_vhost_scsi_dev_construct(name, cpumask) < 0) {
			return -1;
		}

		vdev = spdk_vhost_dev_find(name);
		assert(vdev);

		for (i = 0; spdk_conf_section_get_nval(sp, "Dev", i) != NULL; i++) {
			dev_num_str = spdk_conf_section_get_nmval(sp, "Dev", i, 0);
			if (dev_num_str == NULL) {
				SPDK_ERRLOG("%s: Invalid or missing Dev number\n", name);
				return -1;
			}

			dev_num = (int)strtol(dev_num_str, NULL, 10);
			lun_name = spdk_conf_section_get_nmval(sp, "Dev", i, 1);
			if (lun_name == NULL) {
				SPDK_ERRLOG("%s: Invalid or missing LUN name for dev %d\n", name, dev_num);
				return -1;
			} else if (spdk_conf_section_get_nmval(sp, "Dev", i, 2)) {
				SPDK_ERRLOG("%s: Only one LUN per vhost SCSI device supported\n", name);
				return -1;
			}

			if (spdk_vhost_scsi_dev_add_dev(vdev, dev_num, lun_name) < 0) {
				return -1;
			}
		}

		sp = spdk_conf_next_section(sp);

	}

	return 0;
}

static void
free_task_pool(struct spdk_vhost_scsi_dev *svdev)
{
	struct spdk_vhost_virtqueue *vq;
	uint16_t i;

	for (i = 0; i < svdev->vdev.num_queues; i++) {
		vq = &svdev->vdev.virtqueue[i];
		if (vq->tasks == NULL) {
			continue;
		}

		spdk_dma_free(vq->tasks);
		vq->tasks = NULL;
	}
}

static int
alloc_task_pool(struct spdk_vhost_scsi_dev *svdev)
{
	struct spdk_vhost_virtqueue *vq;
	struct spdk_vhost_scsi_task *task;
	uint32_t task_cnt;
	uint16_t i;
	uint32_t j;

	for (i = 0; i < svdev->vdev.num_queues; i++) {
		vq = &svdev->vdev.virtqueue[i];
		task_cnt = vq->vring.size;
		if (task_cnt > SPDK_VHOST_MAX_VQ_SIZE) {
			/* sanity check */
			SPDK_ERRLOG("Controller %s: virtuque %"PRIu16" is too big. (size = %"PRIu32", max = %"PRIu32")\n",
				    svdev->vdev.name, i, task_cnt, SPDK_VHOST_MAX_VQ_SIZE);
			free_task_pool(svdev);
			return -1;
		}
		vq->tasks = spdk_dma_zmalloc(sizeof(struct spdk_vhost_scsi_task) * task_cnt,
					     SPDK_CACHE_LINE_SIZE, NULL);
		if (vq->tasks == NULL) {
			SPDK_ERRLOG("Controller %s: failed to allocate %"PRIu32" tasks for virtqueue %"PRIu16"\n",
				    svdev->vdev.name, task_cnt, i);
			free_task_pool(svdev);
			return -1;
		}

		for (j = 0; j < task_cnt; j++) {
			task = &((struct spdk_vhost_scsi_task *)vq->tasks)[j];
			task->svdev = svdev;
			task->vq = vq;
			task->req_idx = j;
		}
	}

	return 0;
}

/*
 * A new device is added to a data core. First the device is added to the main linked list
 * and then allocated to a specific data core.
 */
static int
spdk_vhost_scsi_start(struct spdk_vhost_dev *vdev, void *event_ctx)
{
	struct spdk_vhost_scsi_dev *svdev;
	uint32_t i;
	int rc;

	svdev = to_scsi_dev(vdev);
	if (svdev == NULL) {
		SPDK_ERRLOG("Trying to start non-scsi controller as a scsi one.\n");
		rc = -1;
		goto out;
	}

	rc = alloc_task_pool(svdev);
	if (rc != 0) {
		SPDK_ERRLOG("%s: failed to alloc task pool.\n", vdev->name);
		goto out;
	}

	for (i = 0; i < SPDK_VHOST_SCSI_CTRLR_MAX_DEVS; i++) {
		if (svdev->scsi_dev[i] == NULL) {
			continue;
		}
		spdk_scsi_dev_allocate_io_channels(svdev->scsi_dev[i]);
	}
	SPDK_NOTICELOG("Started poller for vhost controller %s on lcore %d\n", vdev->name, vdev->lcore);

	spdk_vhost_dev_mem_register(vdev);

	spdk_poller_register(&svdev->requestq_poller, vdev_worker, svdev, 0);
	spdk_poller_register(&svdev->mgmt_poller, vdev_mgmt_worker, svdev,
			     MGMT_POLL_PERIOD_US);
out:
	spdk_vhost_dev_backend_event_done(event_ctx, rc);
	return rc;
}

struct spdk_vhost_dev_destroy_ctx {
	struct spdk_vhost_scsi_dev *svdev;
	struct spdk_poller *poller;
	void *event_ctx;
};

static void
destroy_device_poller_cb(void *arg)
{
	struct spdk_vhost_dev_destroy_ctx *ctx = arg;
	struct spdk_vhost_scsi_dev *svdev = ctx->svdev;
	uint32_t i;

	if (svdev->vdev.task_cnt > 0) {
		return;
	}


	for (i = 0; i < svdev->vdev.num_queues; i++) {
		spdk_vhost_vq_used_signal(&svdev->vdev, &svdev->vdev.virtqueue[i]);
	}

	for (i = 0; i < SPDK_VHOST_SCSI_CTRLR_MAX_DEVS; i++) {
		if (svdev->scsi_dev[i] == NULL) {
			continue;
		}
		spdk_scsi_dev_free_io_channels(svdev->scsi_dev[i]);
	}

	SPDK_NOTICELOG("Stopping poller for vhost controller %s\n", svdev->vdev.name);
	spdk_vhost_dev_mem_unregister(&svdev->vdev);

	free_task_pool(svdev);

	spdk_poller_unregister(&ctx->poller, NULL);
	spdk_vhost_dev_backend_event_done(ctx->event_ctx, 0);
}

static int
spdk_vhost_scsi_stop(struct spdk_vhost_dev *vdev, void *event_ctx)
{
	struct spdk_vhost_scsi_dev *svdev;
	struct spdk_vhost_dev_destroy_ctx *destroy_ctx;

	svdev = to_scsi_dev(vdev);
	if (svdev == NULL) {
		SPDK_ERRLOG("Trying to stop non-scsi controller as a scsi one.\n");
		goto err;
	}

	destroy_ctx = spdk_dma_zmalloc(sizeof(*destroy_ctx), SPDK_CACHE_LINE_SIZE, NULL);
	if (destroy_ctx == NULL) {
		SPDK_ERRLOG("Failed to alloc memory for destroying device.\n");
		goto err;
	}

	destroy_ctx->svdev = svdev;
	destroy_ctx->event_ctx = event_ctx;

	spdk_poller_unregister(&svdev->requestq_poller, NULL);
	spdk_poller_unregister(&svdev->mgmt_poller, NULL);
	spdk_poller_register(&destroy_ctx->poller, destroy_device_poller_cb, destroy_ctx,
			     1000);

	return 0;

err:
	spdk_vhost_dev_backend_event_done(event_ctx, -1);
	return -1;
}

int
spdk_vhost_init(void)
{
	return 0;
}

void
spdk_vhost_fini(void)
{
}

static void
spdk_vhost_scsi_config_json(struct spdk_vhost_dev *vdev, struct spdk_json_write_ctx *w)
{
	struct spdk_scsi_dev *sdev;
	struct spdk_scsi_lun *lun;
	uint32_t dev_idx;
	uint32_t lun_idx;

	assert(vdev != NULL);
	spdk_json_write_name(w, "scsi");
	spdk_json_write_object_begin(w);
	for (dev_idx = 0; dev_idx < SPDK_VHOST_SCSI_CTRLR_MAX_DEVS; dev_idx++) {
		sdev = spdk_vhost_scsi_dev_get_dev(vdev, dev_idx);
		if (!sdev) {
			continue;
		}

		spdk_json_write_name(w, "scsi_dev_num");
		spdk_json_write_uint32(w, dev_idx);

		spdk_json_write_name(w, "id");
		spdk_json_write_int32(w, spdk_scsi_dev_get_id(sdev));

		spdk_json_write_name(w, "device_name");
		spdk_json_write_string(w, spdk_scsi_dev_get_name(sdev));

		spdk_json_write_name(w, "luns");
		spdk_json_write_array_begin(w);

		for (lun_idx = 0; lun_idx < SPDK_SCSI_DEV_MAX_LUN; lun_idx++) {
			lun = spdk_scsi_dev_get_lun(sdev, lun_idx);
			if (!lun) {
				continue;
			}

			spdk_json_write_object_begin(w);

			spdk_json_write_name(w, "id");
			spdk_json_write_int32(w, spdk_scsi_lun_get_id(lun));

			spdk_json_write_name(w, "name");
			spdk_json_write_string(w, spdk_scsi_lun_get_name(lun));

			spdk_json_write_object_end(w);
		}

		spdk_json_write_array_end(w);
	}

	spdk_json_write_object_end(w);
}

SPDK_LOG_REGISTER_TRACE_FLAG("vhost_scsi", SPDK_TRACE_VHOST_SCSI)
SPDK_LOG_REGISTER_TRACE_FLAG("vhost_scsi_queue", SPDK_TRACE_VHOST_SCSI_QUEUE)
SPDK_LOG_REGISTER_TRACE_FLAG("vhost_scsi_data", SPDK_TRACE_VHOST_SCSI_DATA)